共查询到20条相似文献,搜索用时 375 毫秒
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以2,4-二氯-6-辛氧基-1,3,5-三嗪为原料,经Kumada偶联及胺化两步反应合成了三嗪胺衍生物:4-(9-蒽基)-6-辛氧基-1,3,5-三嗪-2-胺(AOOTA),总产率为38%.通过紫外-可见吸收光谱及荧光光谱研究了氯仿溶液中AOOTA在乙酸(HOAc)及三氟乙酸(TFA)作用下的光谱行为.研究发现AOOTA与HOAc在基态及激发态下均不能发生双氢键作用,而AOOTA与TFA相互作用基态下形成双氢键复合物,激发态下由于分子中蒽基及辛氧基与三嗪环间的C—C单键以及C—O单键的自由旋转,从而使得AOOTA与TFA分子间不能形成有效的氢键相互作用. 相似文献
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由3-氯-1-丙醇法合成3-甲氧基-1-丙醇确定的较佳工艺条件为:甲醇钠/3-氯-1-丙醇摩尔比=1.4~1.8,甲醇钠的甲醇溶液质量分数=27%~30%,滴加温度及反应温度均为70℃,滴加时间为1h,反应时间为5h,并确定了中和方法及精馏提纯条件。产品收率在85%以上,较文献报道产品收率有明显提高。 相似文献
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以对甲苯磺酸为催化荆,采用操作简便、绿色环保的无溶剂合成方法,通过Pechmann反应成功合成了未见文献报道的标题化合物.结构经1HNMR及MS确证. 相似文献
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《Ceramics International》2016,42(13):14313-14325
Bioactive glasses and glassceramics have been used in both bone repair and tissue engineering applications. An important feature of bioactive glasses and glassceramics, which enables them to be used for desired application, is their biological activity. This activity is manifested by the ability of these materials to form a stable bond with bone tissue (bioactivity) and, in some cases, their ability to promote/initiate osteogenesis (osteoinductivity). A stable material-bone bonding (i.e. bioactivity) results from specific material surface reactions leading to hydroxyapatite (HAp) formation on the material surface. Bioactivity of materials is often evaluated in vitro and the ability of materials to form HAp-like surface layer is usually studied after immersion/incubation of materials in simulated body fluid (SBF). Biological activity of materials can be also defined as their ability to induce specific cell responses leading to faster regeneration of bone tissue. It may be manifested by materials supporting bone cell attachment, proliferation and differentiation (biocompability/osteconductivity), and/or by materials inducing/promoting the expression of multiple bone-related genes that drive osteogenesis (osteoinductivity). Osteoinductivity is often verified in vivo by the materials capability to form bone at etopic (i.e. extraskeletal) sites. However, a lot of in vitro call-based experiments are now offered to determine osteoinductive properties of biomaterials. This review focuses on the silica-based glasses and glass-ceramics, in particular, the sol-gel derived ones, and summarizes their bioactivity and osteoinductivity as major determinants of their biological activity. We highlight the chemistry of bioglasses and glassceramics that affects not only the formation of a stable implant/bone bonding by HAp layer, but also drives the cell response in vitro and in vivo. 相似文献
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相比已经完善丰富的开采和勘探技术,油气的运输以及储存却仍然存在不足之处。我国对能源安全提出更加严格要求的同时,对区域经济的发展规划也有足够重视。因此,保障油气管道的安全则成为了我国能源安全战略的重中之重。在阐释油气管道现阶段在储运安全保障技术发展状况的基础上,分析了现存的问题及解决问题的手段,并指出未来可能使用的目标策略,为今后研究者提供一定程度上的借鉴经验。 相似文献
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K. Košuti?B. Kunst 《Desalination》2002,150(2):113-120
The variations of porosity parameters of some reverse osmosis (RO) and nanofiltration (NF) polyamide thin-film composite membranes were determined in order to explain the changes of membranes' performances caused by membrane fouling and chemical cleaning of the fouled membranes. The pore size distribution curves and the effective number of pores in the membrane surface indicated plugging of the tight network pores in the membrane surface and even their disappearance during fouling. The enlargement of the wider aggregate pores was responsible for the noticed reduction in salt rejection. The initial pore structure of the fouled RO membrane was restored by immediate chemical cleaning. A delay of chemical cleaning of the fouled membranes led to irreversible changes in the porous structure of both the RO and NF membranes, which were caused by a microbial activity. 相似文献
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Due to their non-toxic nature, biodegradability and production from renewable resources, research has shown an increasing interest in the use of biosurfactants in a wide variety of applications. This paper reviews the characterization of rhamnolipid and sophorolipid biosurfactants based on their hydrophilicity/hydrophobicity and their ability to form microemulsions with a range of oils without additives. The use of the biosurfactants in applications such as detergency and vegetable oil extraction for biodiesel application is also discussed. Rhamnolipid was found to be a hydrophilic surfactant while sophorolipid was found to be very hydrophobic. Therefore, rhamnolipid and sophorolipid biosurfactants in mixtures showed robust performance in these applications. 相似文献
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文章采用离子色谱法/电导检测器,测定了蔬菜水果样品中的硝酸盐和亚硝酸的含量。实验选取并优化样品前处理方法,获得无色透明的溶液后,经0.45μm过滤器过滤后得到待测液,最后自动进样,离子色谱法进行样品测定,以10 mmol/L KOH溶液为淋洗液,相对标准偏差:NO3-为0.38%,NO2-为0.54%;回收率:NO3-为98.8%~99.7%,NO2-为98.6%~99.9%。本方法操作简便快速,且具有仪器稳定性好、测定结果准确可靠的特点。在被测定蔬菜水果中,硝酸盐和亚硝酸盐含量都在较低浓度水平,NO3-:16.8~21.9 mg/kg,NO2-:0.0887~0.164 mg/kg。最后讨论了几种蔬菜水果样品储藏过程中硝酸盐与亚硝酸盐的含量变化情况。 相似文献
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油气田的开发建设一直是我国石油行业中的重中之重。随着我国石油行业的快速发展,各项领域对石油与天然气的需求也越来越大。但是,随着石油与天然气的大力开采,对环境产生了不良的影响。对此,通过对油气田的开发、油气田开发建设对环境的影响以及环境的保护对策等方面进行了简略的说明,希望对我国以后油气田开发建设有一定的指导作用。 相似文献
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苯乙烯是重要的石油化工原料。本文介绍了国内外苯乙烯生产的发展概况,合成乙苯,苯乙烯所用的催化剂种类,并就苯乙烯生产及催化剂的发展趋势提出了自己的观点。 相似文献
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